Along with the development of communication technology, in order to enhance the competitiveness of future networks, the 3rd Generation Partnership Project (3GPP) is researching a brand-new evolution network. Referring to FIG. 1, a system architecture of the evolution network includes the following.
An evolved universal mobile telecommunications system (UMTS) territorial radio access network (E-UTRAN) is configured to implement radio-related functions of the evolution network. A mobility management entity (MME) takes charge of mobility management of a control plane, which includes management of user context and mobility state, and assignment of a user temporary identity. A serving gateway (serving GW) is a user plane anchor point between 3GPP communication networks, and terminates the interface towards E-UTRAN. A packet data network gateway (PDN GW) is a user plane anchor point between the 3GPP communication network and a non-3GPP communication network, and terminates the interface towards the external PDN. A policy and charging rule function (PCRF) is configured to perform functions including policy control decision and flow based charging control. A home user server (HSS) is configured to store subscription information of user.
A UMTS territorial radio access network (UTRAN) and a global system for mobile communication/enhanced data rates for GSM evolution (GSM/EDGE) radio access network (GERAN) are configured to implement the radio-related functions in the existing general packet radio service (GPRS)/UMTS network. A serving GPRS supporting node (SGSN) is configured to implement routing forward, mobility management, session management, user information storage, and other functions in the GPRS/UMTS network.
Non-3GPP Internet Protocol communication networks (non-3GPP IP Access) are communication networks defined by the non-3GPP organizations, for example, a wireless local area network (WLAN), a worldwide interoperability for microwave access (WiMAX), and a code division multiple access (CDMA) network.
An authentication, authorization and accounting server (AAA server) is configured to execute access authentication, authorization, and accounting functions on user equipment (UE).
In order to reduce mobility management processing of the UE among the different communication networks, the processing of the inter system mobility between the GERAN/UTRAN and the E-UTRAN (inter 3GPP access system mobility) can be reduced through an idle mode signaling reduction (ISR) mechanism in a 3GPP communication network.
In conventional systems, when the user using the ISR mechanism moves to another New MME, the New MME acquires context information of the UE from an Old SGSN and an Old MME. Then, the New MME judges whether the UE uses the ISR mechanism, and notifies the HSS of using situation of the ISR mechanism. The HSS then notifies the Old MME to detach the user.
The processing processes of a 3GPP communication network are specific to a 3GPP communication network. When the UE moves to the non-3GPP communication network, the specific processing processes in the 3GPP communication network cannot be processed in the non-3GPP communication network, that is, resources of the UE in the 3GPP communication network cannot be released.